1. Field of the Invention
The invention pertains to the field of lawn mowers. More particularly, the invention pertains to a lawn mower wherein the lawn mower chassis rests on top of a ground-following lawn mower cutter deck.
2. Description of Related Art
A typical lawn mower chassis and a typical ground-following cutter deck of the prior art each include supports holding the chassis and cutter deck in relation to the ground. Typically, these supports are wheels, but they optionally comprise rollers, skids, or other suitable support means. One problem in the prior art is that such a combination of conventional elements generally does not maintain an even grass cut, due to the up and down vertical motion inherent in such systems. In particular, chassis roll and pitch and cutter deck bouncing can affect adversely the evenness of the grass cut.
FIG. 1 shows a typical ground-following lawn mower cutter deck of the prior art. This design has a cutter deck frame 3 from which cutter deck 10 hangs. Cutter deck 10 includes deck wheels 9 and a deck lift assembly that includes deck lift mechanism 16, chains or cables (not shown), and deck lift linkages 5. Deck lift mechanism 16 is what the operator physically actuates to lift the cutter deck, for example, when not mowing. Typically, the cutting height adjustment is made after the deck lift mechanism has been actuated and the cutter deck is in its upward position. Each of the foregoing parts are common in prior art designs for adjusting and maintaining the lawn mower""s cutting height. However, typical lawn mowers of the prior art can also include other conventional designs. For example, the wheels can be mounted directly from the cutter deck and cantilevered from that position (not shown), or the cutter deck 10 can be connected to the chassis frame 2 through the use of cutter deck pusher bars 15, or other similar conventional means. A conventional chassis frame 2 is typically one of the main components of the lawn mower. In many cases, chassis frame 2 is the structure to which most of the other parts of the lawn mower are attached. The prior art lawn mower typically has three to four wheels that support its weight and allow for its movement over a surface, such as the lawn being cut. Typically, all parts having to do with the lawn mower""s speed and direction are attached to the chassis frame.
FIGS. 2 and 3 illustrate a typical riding lawn mower, comprising a lawn or garden tractor and a ground-following cutter deck attached to its chassis frame, such that they operate as one machine. FIG. 2 shows a typical lawn/garden tractor of the prior art with a prior art ground-following lawn mower deck 10 attached to the tractor""s chassis frame 2. Rear wheels 7 are typically the drive wheels, which dictate the forward and reverse motion and speed of the vehicle. Mounted to the front of chassis frame 2 are chassis steering wheels 17, comprising steering means for turning the vehicle. The ground-following cutter deck 10 is attached by arms 18 to chassis frame 2, such that cutter deck 10 responds to the ground contours independently of chassis response to ground contours. Cutter deck 10 is supported by deck wheels 9.
FIG. 3 shows a typical zero turning-radius lawn mower of the prior art, comprising a ground-following cutter deck attached to chassis frame 2. Rear wheels 7 are typically the drive wheels, which dictate the forward and reverse motion and speed of the vehicle. Mounted to the front of chassis frame 2 are chassis support wheels 19, which are merely chassis supports (i.e., not steering means). The ground-following cutter deck assembly is located behind chassis support wheels 19. Cutter deck height adjustment and attachment are accomplished via conventional means, which are well known in the art. Cutter deck 10 is supported by deck wheels 9 mounted to cutter deck frame 3. The entire cutter deck assembly is then connected to chassis frame 2 by radius rods 8, which transfer speed and direction from the chassis. Cutter deck 10 responds to ground contours independently of chassis response to the ground contours.
The combination of a ground-following cutter deck and a conventional lawn mower chassis, be it a tractor or a zero turning radius lawn mower (as described above), allows both components to interact with the surface contours of the ground, independently of each others"" reactions to ground surface contours. However, in the prior art designs, the cutter deck can bounce and thereby fail to follow the ground contours. In attempts to solve this problem, some prior art lawnmowers have been designed such that the cutter deck hangs directly from the chassis frame, whereby the cutter deck responds directly to chassis movement, rather than to the ground contours. Such designs are typically referred to in the art as a xe2x80x9cfloating deckxe2x80x9d design, because the cutter deck xe2x80x9cfloatsxe2x80x9d over the ground surface, as opposed to a ground-following deck, which typically rolls over the ground.
However, the floating deck design does not completely resolve the common problems with ground-following cutter decks, and the floating deck has its own inherent problems. More particularly, floating deck designs can result in an uneven grass cut, when uneven or bumpy ground contours cause the chassis, from which the floating deck hangs, to move up and down vertically, and pitch and roll, thereby causing the floating deck also to move up and down, and pitch and roll, thus resulting in an uneven grass cut.
Briefly stated, an improved lawn mower design includes a chassis assembly having one or more drive wheels, a ground-following cutter deck assembly attached to the chassis, and rolling means attached to the cutter deck, wherein the chassis and the cutter deck are arranged such that the rolling or sliding means and the drive wheels support the chassis for movement over a surface. The ground-following cutter deck thereby reacts to the ground contours independent of the reactions of the chassis, and the combined weight of chassis and cutter deck keep the deck from bouncing, thus, the ground-following cutter deck follows the ground contours evenly.